The filmmakers asked people all around the world to shoot a little of their lives, all on July 24, 2010, and then share it with them.
They received 81,000 videos totaling 4,500 hours of footage.
"It's something that could only really be done in the last few years when you have cellphones that have great cameras on them, when you have camcorders that cost a few hundred dollars, and where you can use YouTube and you can upload everything and communicate with people," described director Kevin MacDonald.
The filmmakers hired 24 people to help watch it all. It went from 4,500 hours down to 350 to 10 to about an hour and a half.
"It does everything that a movie does or should do. It makes you cry and it makes you laugh and you have a good time and you really relate to all these characters," MacDonald described.
Kevin McMahon is one character in the film. The former national diving champ got clever with a tiny HD camera.
"It was pretty easy to strap it on my ankle, on my head, on my chest," explained McMahon. After watching the entire movie, McMahon said the film has a lot of heart.
"I'm just really blown away with what they were able to do with it and how much power and emotion comes out of that," he said. "I think it does raise consciousness, you know, and brings the world together."
Director MacDonald said he learned a great deal while making the film.
"Really what I learned was when you strip away all the kind of what seems to make us different, we are the same."
"Life in a Day" opens in limited release July 29.